BUUCTF_Re_不一样的flag
无壳,ida伪代码:
int __cdecl __noreturn main(int argc, const char **argv, const char **envp)
{
char v3[29]; // [esp+17h] [ebp-35h] BYREF
int v4; // [esp+34h] [ebp-18h]
int v5; // [esp+38h] [ebp-14h] BYREF
int i; // [esp+3Ch] [ebp-10h]
char v7[12]; // [esp+40h] [ebp-Ch] BYREF
__main();
v4 = 0;
strcpy(v3, "*11110100001010000101111#");
while ( 1 )
{
puts("you can choose one action to execute");
puts("1 up");
puts("2 down");
puts("3 left");
printf("4 right\n:");
scanf("%d", &v5);
if ( v5 == 2 )
{
++*(_DWORD *)&v3[25];
}
else if ( v5 > 2 )
{
if ( v5 == 3 )
{
--v4;
}
else
{
if ( v5 != 4 )
LABEL_13:
exit(1);
++v4;
}
}
else
{
if ( v5 != 1 )
goto LABEL_13;
--*(_DWORD *)&v3[25];
}
for ( i = 0; i <= 1; ++i )
{
if ( *(int *)&v3[4 * i + 25] < 0 || *(int *)&v3[4 * i + 25] > 4 )
exit(1);
}
if ( v7[5 * *(_DWORD *)&v3[25] - 41 + v4] == 49 )
exit(1);
if ( v7[5 * *(_DWORD *)&v3[25] - 41 + v4] == 35 )
{
puts("\nok, the order you enter is the flag!");
exit(0);
}
}
}
看到v3这个奇怪的字符,一共25位,然后有上下左右,
我一直在分析代码,然后想着怎么写脚本,结果,一看
5x5的迷宫,把v3分解成迷宫的样子:
*1111
01000
01010
00010
1111#
#号就是终点,*号就是起点
最后把路径转换成数字就是flag:
flag{222441144222}